Pendulum Tracker—SimuFísica®: a web-based tool for real-time measurement of oscillatory motion

Abstract We present Pendulum Tracker, a computer vision-based application that enables real-time measurement of the oscillatory motion of a physical pendulum. Integrated into the educational platform SimuFísica, the system uses the OpenCV.js library and runs directly in the browser, working on computers, tablets, and smartphones. The application automatically detects the pendulum’s position via the device’s camera, displaying in real time the angle-versus-time graph and estimates of the oscillation period. Experimental case studies demonstrate its effectiveness in measuring the period, determining gravitational acceleration, and analysing damped oscillations. The results show excellent agreement with theoretical predictions, confirming the system’s accuracy and its applicability in educational contexts. Its web-based interface and support for data export make Pendulum Tracker suitable for a variety of experimental physics activities. A pilot classroom implementation suggests that the tool also helps students connect observed motion with its graphical representation.